V4L/DVB (12514): sh_mobile_ceu_camera: add a control for the camera low-pass filter

Use the V4L2_CID_SHARPNESS control to switch SH-mobile camera low-pass filter.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>